Eluted Soluble Silica Content in Rice Husk Charcoal Produced by Rice Husk Burner

Abstract

This study aims to compare burner combustion method with conventional method from the viewpoint of total amount of eluted soluble silica in rice husk charcoal (RHC). RHC was prepared in an electric furnace by controlling the combustion temperature and time. The amount of eluted soluble silica in RHC was measured by the molybdenum blue absorptiometric method. The amount of unburned carbon and the crystallization of silica were measured by weight change between RHC production and by the specific surface area and pore volume of RHC, respectively. As a result, RHC combusted at 900 °C for 3 min as a developed rice husk burner contained 60% of the amount of eluted soluble silica in RHC combusted by conventional method at 400°C for 60 min. With regard to the mechanism of silica elusion, in short-term combustion assuming a developed rice husk burner, high temperature was suitable for increasing the amount of eluted soluble silica because it was determined by eliminating the plant fiber covering silica in rice husk. On the other hand, in long-term combustion assuming conventional method, low temperature combustion showed the possibility for increasing the amount of eluted soluble silica because it was determined by the crystallization of silica.